JPS6240291Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a helium refrigeration system for cooling an object to be cooled to a temperature of 4°C or less.

In recent years, various types of refrigeration equipment of 4ⓓ or less have been developed for cooling objects to be cooled such as large-capacity exhaust cryopumps and superconducting magnets. Conventional helium refrigeration equipment of 4ⓓ or less is a device specially designed according to user requirements, and is not versatile.

The purpose of the present invention is to obtain a versatile helium liquefaction refrigerator of 4 ㎓ or less by using a helium liquefaction refrigerator of 4 〓 or more that has already been put into practical use.

An example of a conventional helium liquefaction refrigeration system with a capacity of 4ⓓ or less is shown in FIG. In the figure, 1 is a helium compressor, 10 is a pressure reducing device, and 3 is a helium liquefaction refrigerator. The helium liquefaction refrigerator 3 is a three-fluid heat exchanger HX-1 between high-pressure helium gas compressed by the helium compressor 1, low-pressure helium gas at almost atmospheric pressure, reduced-pressure helium gas lower than atmospheric pressure, etc.
~HX-5, expanders T-1, T-2, liquefied helium reservoir 4, another heat exchanger HX-6, low temperature control valve V-
1, V-2, etc. are housed in a heat insulating container.

The operation will be explained according to FIG. 1. High pressure helium gas obtained by compressing atmospheric pressure helium gas by a helium compressor 1 is supplied to a helium liquefaction refrigerator 3 through a conduit 2. High pressure helium gas heat exchanger
It is cooled by HX-1 to HX-5 and expanders T-1 and T-2, liquefied by a low temperature control valve V-1, and stored in a liquefied helium reservoir 4 at atmospheric pressure. The vaporized helium gas in the liquefied helium reservoir 4 is transferred to the heat exchanger HX.
-5 to HX-1, is recovered to a low pressure tank 11, and compressed by a helium compressor 1. On the other hand, the liquefied helium at atmospheric pressure in the liquefied helium reservoir 4 is reduced in pressure by the low temperature control valve V-2 and is supplied to the object to be cooled 7 via the low temperature transfer pipe 6. The return gas from the object to be cooled 7 is guided to the helium liquefaction refrigerator 3 via the low-temperature transfer pipe 8, and is sucked into the pressure reducing device 10 via the heat exchangers HX-6 to HX-1, where it is compressed to atmospheric pressure.

When initially cooling the object 7 to be cooled, liquefied helium is supplied from the liquefied helium reservoir 4 to the object 7 to be cooled. At this time, the return gas is supplied to the valve V-5 in a separate system until the object 7 to be cooled is cooled to the liquefied helium temperature.
It is heated to room temperature through a conduit 12 by a temperature riser 13 and then sucked into a pressure reducing device 10.

When the helium liquefaction refrigerator 3 is stopped, the vaporized helium gas is collected into the high pressure tank 14.

The above-mentioned conventional helium refrigeration system having a capacity of 4ⓓ or less has the following drawbacks.

(1) It needs to be specially designed based on each requirement, and therefore the cost is high.

(2) Since the heat exchanger in the helium liquefaction refrigerator 3 is a three-fluid type multistage heat exchanger, the pressure loss in the pressure reduction line is large, and the pressure reduction device 10 needs to have a large capacity.

(3) When the variation in the amount of heat load on the object to be cooled 7 is large,
It is difficult to maintain the temperature balance within the helium liquefaction refrigerator 3.

(4) Since there is an expander inside the helium liquefaction refrigerator that has a high failure rate, it will be difficult to maintain the temperature below 4〓 in the event of a failure.

(5) During the initial cooling of the object to be cooled 7, that is, when cooling from room temperature to the helium liquefaction temperature, if the gas is returned to the helium liquefaction refrigerator 3, the temperature balance of the heat exchanger will be disrupted, so it is collected in a separate line. At this time, cold recovery is not possible.

(6) Since the helium liquefaction refrigerator 3 is a three-fluid type (fluid for high pressure, low pressure, reduced pressure, etc.), the control equipment is complicated and operation is difficult.

The purpose of this invention is to eliminate the drawbacks of the conventional refrigeration equipment as described above, and it uses a helium liquefaction refrigeration equipment of 4 or more that has been put into practical use.
By combining this with a helium decompression device and a regenerative heat exchange device, a helium refrigeration device of 4ⓓ or less is constructed by each independent equipment configuration.

The regenerative heat exchange device is configured to reliquefy helium gas by cooling the gas returned from the object to be cooled.

An embodiment of the present invention will be described with reference to FIG.

The illustrated device is a helium refrigeration device that generates 4 degrees of cold or less, including a helium compressor 101, a helium liquefaction refrigerator 103, and a liquefied helium container 10.
4, the body to be cooled 107, a regenerative heat exchange device 125, a temperature riser 113, a helium pressure reduction device 110, a low pressure tank 111, a high pressure recovery tank 114, etc. Among these, helium compressor 101, helium liquefaction refrigerator 103, liquefied helium container 10
4. The combination of the low-pressure tank 111 and the high-pressure recovery tank 114 is known as a helium liquefaction refrigeration system of 4 or more and is commercially available.

That is, the present invention adds a regenerative heat exchanger 125, a temperature riser 113,
By adding a helium decompression device 110, the helium refrigeration system can be made into a helium refrigeration system of 4ⓓ or less.

The basic flow of the helium refrigeration system shown in FIG. 2 is as follows.

(1) Produce and store liquefied helium of 4ⓓ or more in the liquefied helium container 104 using a 4ⓓ or more helium liquefaction refrigeration device.

(2) The liquefied helium in the liquefied helium container 104 is transferred to the object to be cooled 107 by the helium decompression device 110.
through the transfer pipe 106.

(3) The inlet control valve V-10 to the object to be cooled 107 reduces the pressure of the liquefied helium of 4ⓓ or more to 4ⓓ or less.

(4) Helium gas vaporized by the heat load on the object to be cooled 107 is guided to the regenerative heat exchange device 125 via the transfer pipe 112.

(5) The helium gas led to the regenerative heat exchange device 125 is heated by exchanging heat with high-pressure helium gas in the heat exchanger 126, and heated to normal temperature helium gas in the temperature riser 113, and then sent to the helium decompression device 110. is attracted to.

(6) The sucked helium gas is recovered by the helium pressure reducing device 110 into the low pressure tank 111 at a pressure slightly higher than atmospheric pressure, and is recompressed by the helium compressor 101.

(7) High-pressure helium gas compressed by the helium compressor 101 is supplied to the helium liquefaction refrigerator 103 and the regenerative heat exchange device 125.

The high pressure helium gas supplied to the helium liquefaction refrigerator 103 is transferred to the heat exchanger HX'-1 or HX'-
5. It is cooled by liquefied nitrogen passing through the expanders T'-1, T'-2 and the conduit 115, and liquefied helium gas of 4ⓓ or more is produced by the expansion valve V-8.

On the other hand, the high-pressure helium gas supplied to the regenerative heat exchanger 125 is cooled by the return cold from the object to be cooled 107, and is freely expanded to near atmospheric pressure by the low temperature control valve V-12, and a portion of it is liquefied. It is stored in a liquefied helium container 104.

(8) The entire amount of vaporized helium gas in the liquefied helium container 104 (mainly caused by the expansion valve V-8 and the low temperature control valve V-12) is transferred to the helium liquefaction refrigerator 1.
It will be collected on 03. In this case, the amount of vaporized cold helium gas increases because vaporized helium gas is added by the low temperature control valve V-12 of the regenerative heat exchanger 125.

(9) The increased cold helium gas imparts increased refrigeration to the high-pressure helium gas by the heat exchanger in the helium liquefaction refrigerator 103, thus increasing the liquefaction capacity of the helium liquefaction refrigerator 103.

(10) This helium gas is helium liquefaction refrigerator 10
3 to a low pressure tank 111 and a helium compressor 101.

(11) When the helium liquefaction refrigerator 103 is stopped, the high pressure recovery tank 114 is
Helium gas is recovered.

If the helium flow rate becomes unbalanced as the suction pressure of the helium compressor 101 becomes higher and the discharge pressure becomes higher than the specified value during operation of the helium refrigeration system, helium gas is automatically recovered to the high-pressure recovery tank 114. Conversely, when the pressure in the low pressure tank 111 decreases below the specified level, helium gas is automatically supplied from the high pressure recovery tank 114.

(12) Next, the function of the regenerative heat exchange device 125 will be explained. This device 125 is an independent device from the helium liquefaction refrigerator 103, and includes a heat exchanger 126 and a low temperature control valve V-12 built in an insulated container.

The heat exchanger 126 is a device that exchanges heat between the cold helium gas from the object to be cooled 107 whose pressure has been reduced to below atmospheric pressure and the high-pressure helium gas supplied from the helium compressor 101. -12 is a heat exchanger 126 in which high pressure helium gas is supplied to the outlet of the heat exchanger from about 5 to
It functions as a temperature control valve that opens in response to a command from the detector S-2, which detects this temperature when it has cooled to a temperature of 7. It has the role of an expansion valve (Joule-Thomson valve) that liquefies a part of the liquid.

The pressure of the high-pressure helium gas supplied is preferably 6 to 20 atmospheres.

(13) Initial cooling of the object to be cooled 107 by this device,
That is, cooling from room temperature to a temperature of 4°C or less is performed as follows.

Liquefied helium is produced and stored in a liquefied helium container 104 by a helium compressor 101 and a helium liquefaction refrigerator 103. Next, the liquefied helium in the liquefied helium container 104 is transferred to the object to be cooled 107 by the helium decompression device 110 and cooled. The helium gas vaporized in the object to be cooled 107 is pre-cooled in the regenerative heat exchange device 125, heated to room temperature in the temperature riser 113, and then sucked into the helium decompression device 110. Helium decompression device 110
The helium gas sucked into is compressed to about atmospheric pressure and guided to the helium compressor 101. Note that unless the high-pressure helium gas in the regenerative heat exchange device 125 is cooled to a temperature at which the low temperature control valve V-12 operates, the valve is closed and no flow occurs.

When the object to be cooled 107 is cooled down to 5 to 7〓, the low temperature control valve V-12 in the regenerative heat exchanger 125 is activated to enter steady operation, and the object to be cooled 107 is
〓 Cooled down to below.

(14) The functions of the main control equipment in Figure 2 are as follows.

Expansion valve V-8 in helium liquefaction refrigerator 103
is attached to a conventional helium liquefaction refrigerator of 4ⓓ or more.

The inlet control valve V-10 of the cooled body 107 is 4〓
This is a pressure regulating valve that brings the above liquefied helium to a temperature of 4㎜ or less by free expansion.

V-11 is a normal temperature pressure reduction control valve that adjusts the suction pressure of the helium pressure reduction device 110. V-
Reference numeral 12 denotes a low temperature control valve, which has the function of opening and closing depending on the high pressure helium outlet temperature of the heat exchanger 126 and the function of reducing the pressure of the high pressure helium to near atmospheric pressure. Further, when the amount of heat load in the cooled body 107 is smaller than the specified value and the amount of liquid stored in the liquefied helium container 104 increases and reaches the specified amount, the signal from the liquid level gauge S-1 is used to control the valve V. -12
closes.

Room temperature high pressure control valve V-13 is helium compressor 1
This is a control valve that recovers high pressure gas to the high pressure recovery tank 114 when the discharge pressure of 01 becomes higher than a specified value. The normal temperature low pressure control valve V-14 is a control valve that supplies pressure from the high pressure recovery tank 114 when the suction pressure of the helium compressor 101 becomes lower than a specified value.

As explained above, according to the present invention, a regenerative heat exchange device 125, a temperature riser 113, and a helium refrigerating device are added to the conventional helium refrigeration system having four or more units, which includes a helium liquefaction refrigerator 103, a helium compressor 101, and a liquefied helium container 104. By adding a pressure reducing device 110, a helium refrigeration device of 4ⓓ or less can be provided, and the manufacturing cost is low. Furthermore, since the device of the present invention has an independent structure in which each main device is configured, each device is easy to operate and control, can be arranged at the installation location, and is easy to maintain and repair.

Decompression helium line is helium liquefaction refrigerator 10
Since the helium liquefaction refrigerator 10 is separated from the
The object to be cooled can be cooled to a desired temperature without affecting the temperature balance of step 3.

Furthermore, the regenerative heat exchange device 125 according to the present invention effectively utilizes the cooling of the reduced pressure helium gas from the object to be cooled 107 to liquefy helium gas and increase the helium liquefaction capacity of the helium liquefaction refrigerator 103. have

The pressure loss of the helium decompression line can be reduced because the heat exchanger is not a multistage three-fluid heat exchanger, and because it is an independent decompression piping, the pipe diameter can be increased.
10 can be made smaller, and the drive motor can be made smaller.

In addition, helium liquefaction refrigerator 1 with a high failure probability
Since the expanders T'-1 and T'-2 in 03 are separated from the vacuum helium line, even if the helium liquefaction refrigerator 103 fails, the liquefied helium container 104
Continuous operation is possible until the liquefied helium inside runs out.

Note that the regenerative heat exchange device 125 can also be precooled during the initial cooling of the object to be cooled 107, and the cooling of the reduced pressure helium gas can be effectively utilized.

The freezing temperature of the object to be cooled 107 is determined by the normal temperature depressurization control valve V-11 of the helium decompression device 110 and the object to be cooled 10.
An arbitrary temperature can be set using the inlet control valve V-10 of No. 7, and the helium liquefaction refrigerator 103 is not affected at this time.

Example 1 An example of the present invention is shown in FIG. This shows a flow for independently cooling a plurality of objects to be cooled 107a, 107b, . . . . Helium compressor 1
01, helium liquefaction refrigerator 103, liquefied helium container 104, temperature riser 113, helium decompression device 1
10, low pressure tank 111, high pressure recovery tank 11
4, etc. are the same as those in FIG. 2, but regenerative heat exchange devices 125a, 125b, etc. are provided for each object to be cooled.
...is provided.

Based on Figure 3, we designed a 3.5〓 helium refrigeration system. The design conditions are as follows.

(1) Helium compressor Suction pressure: atmospheric pressure, discharge pressure: 18atm Processing amount: 1100Nm ³ /hr (2) Helium liquefaction refrigerator (commercial product) Liquefaction capacity: 60-70/hr (4.5〓) (3) Liquefaction Helium container Capacity: 1000 (4) Regenerative heat exchange device: High pressure side: Pressure: 18 atm, flow rate 9 to 10 g/s Reduction side: Pressure: 0.3 atm, flow rate 11 g/s (5) Helium pressure reduction device Suction pressure: 0.2 atm, Discharge pressure: 1.1atm Processing amount: 220Nm ³ /hr As a result of the above, the amount of helium refrigeration in the entire system of the cooled object is
It was about 200W at 3.5〓.

In the first embodiment, a regenerative heat exchange device was used for each of the plurality of objects to be cooled, but it is of course possible to treat a plurality of objects to be cooled using a single regenerative heat exchange device.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the flow of a conventional helium refrigeration system of 4㎜ or less, Fig. 2 is a diagram showing the basic flow of a helium refrigeration system according to the present invention, and Fig. 3 is a diagram showing the basic flow of a helium refrigeration system according to the present invention for a plurality of objects to be cooled. The figure which shows the example of. 101: helium compressor, 103: helium liquefaction refrigerator, 104: liquefied helium container, 107:
Cooled object, 110: Helium decompression device, 111:
Low pressure tank, 114: High pressure recovery tank, 113:
Temperature riser, 106, 108, 112: Conduit, 11
5: Liquefied nitrogen conduit, HX'-1 to HX'-5: Heat exchanger, T'-1, T'-2: Expander, V-8: Expansion valve, V-9: Low temperature stop valve, V- 10: Inlet control valve, V-11: Room temperature pressure reduction control valve, V-13: Room temperature high pressure control valve, V-14: Room temperature low pressure control valve, 12
5: Regenerative heat exchange device, 126: Heat exchanger, V-1
2: Low temperature control valve, S-1: Liquid level gauge, S-2: Temperature detector.

Claims (1)

[Claims for Utility Model Registration] (1) A helium liquefaction refrigerator, a helium compressor that supplies pressurized helium to the helium liquefaction refrigerator, and a liquefied helium that stores the liquefied helium obtained by the helium liquefaction refrigerator. a helium liquefaction refrigeration device for 4 or more units having a container; a control valve for expanding helium provided in a conduit that sends helium from the liquefied helium container to the object to be cooled; cold helium gas generated in the object to be cooled; A helium decompression device that reduces the pressure of helium gas to below atmospheric pressure and recovers it; A regenerative heat exchange device that uses the cold of the depressurized cold helium gas to cool and liquefy helium gas at room temperature and high pressure. A helium refrigeration device capable of continuously cooling an object to be cooled to 4ⓓ or less, characterized in that it has the following. (2) Utility Model Registration Scope In the helium refrigeration device according to claim 1, the regenerative heat exchange device is a device in which a heat exchanger and a low temperature control valve are housed in an insulated container independent of the helium liquefaction refrigerator. The heat exchanger is a device that exchanges heat between high-pressure helium gas compressed to 6 to 20 atmospheres at room temperature and cold helium gas at 4㎓ or less and atmospheric pressure or less, and the low temperature control valve is a Outlet temperature is 5~7
The device is characterized by having both a temperature control function and an expansion valve function, which reduces the pressure of high-pressure helium gas that has been cooled to near atmospheric pressure and liquefies a portion of the helium gas. Helium refrigeration equipment.